# Mean of values before and after a specific element

4 次查看（过去 30 天）
ennes mulla2021-6-29

Hi
I have an array of 1 row and 400 colmun, where all elments values are above 1500. However, I have some elements that have values <50 which are wrong measures and I would like to have the mean of the elments before and after the wrong measured data points and replace it in the main array
For intance, element number 17 is below 50 so I want to take the mean of elment 16 and 18 and replace element 17 with the new mean.

### 采纳的回答

If you have Matlab version greater then R2017a, you can use filloutliers or you can replace the invalid values with NaN an then use fillmissing. You can use "linear" method to replace the ouliers / missing values, which will essentially take the mean of neighbouring values to fill in the outlier / missing value.
% generate test data
a = randi([1000 2000],1,400);
a(randperm(400,10)) = randi([1 50],1,10);
scatter(1:400,a) i = a<= 50;
b = filloutliers(a,'linear','mean');
scatter(1:400,b,[],i,'filled');
colormap jet; c = a;
c(i) = NaN;
c = fillmissing(c,'linear');
scatter(1:400,c,[],i,'filled');
colormap jet; ##### 1 个评论显示隐藏 无
ennes mulla 2021-6-29
It worked!!! thanks a lot buddy! I truly appreciate your help

### 更多回答（1 个）

Mathieu NOE 2021-6-29
hello see code below :
clc
clearvars
% dummy data
x = 1:1:400;
y = 1500 + 50*rand(1,400);
y(40)=35; % first outlier (single value)
y(60:66)=45; % second outliers (multiple values)
yi = y; % keep trace of initial y data (for plot)
all_idx = 1:length(x);
% outlier_idx = abs(y - median(y)) > 2*std(y); % Find outlier idx
outlier_idx = y<50; % Find outlier idx
y(outlier_idx) = []; % remove outlier from dataset
y = interp1(all_idx(~outlier_idx), y, x); % replace outliers by interpolated data
figure(1),plot(x,yi,x,y);

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